Patent GB-650934-A (GB)
Title: Improvements relating to a method of producing power in heat engines through cyclic changes of a gaseous working fluid
IPC: F02G1/04
Filed: 1946-08-27
Abstract: 650,934. Hot gas power plant; combustion product pLant. KREITNER, J., and NETTEL, F. Aug. 27, 1946, No. 25628. Convention date. No. 8, 1941. [Class 7(i)] [Also in Group XXVI] In a heat engine cyclic changes of a gaseous working fluid take place in the following sequence : - (a) Cooled initialcompression followed by uncooled compression to an end point where the entropy and temperature are substantially less than the initial entropy, and greater than the temperature at any point within the. first half of the pressure rise, respectively (b) Isobaric heating to a temperature in excess of the temperature at the compression end point and an entropy greater than the initial entropy. (c) Heated expansion followed by unheated isentropic expansion to a point where the entropy, temperature, and pressure are substahtially larger, substantially lower than at any point within the first half of the pressure drop during expansion and substantially higher than at any point within the first half of the pressure rise during compression and substantially equal to the initial pressure respectively. The uncooled compression covers at least 40 per cent of the pressure difference between the highest and lowest pressures in the system. The isobaric heating may be carried out by direct heating of the workng fluid by burning fuel therein or by indirect heating by surface heat transfer or partly by regeneration of waste heat of the expanded exhaust gases. By substantially larger entropy is meant an increase corresponding to an increase in useful expansion work and by substantially smaller entropy at the end point of compression is meant a decrease in entropy corresponding to a saving in mechanical compression work. Compression may be carried out in a single piece of apparatus or the cooled and uncooled compression may be carried out in separate pieces of apparatus. Formulae are given for determining the temperature rise during compression and the temperature drop during expansion. Fig. 3 shows the theoretical cycle of operations. It consists of isothermic compression 31-32, an isentropic compression 32-33, an isobaric heating 33-34, an isothermic expansion 34-35, an isentropic expansion 35, 36, and isobaric rejection or recooling in the case of a closed cycle 36-31. In the actual cycle the lines 32, 33 and 35, 36 incline slightly from the vertical. The cooled compression may be carried out by intercooling in a number of stages approximating isothermal compression and the heated expansion may be carried out by reheating in a number of stages approximating isothermal expansion With compression according to an irregular curve or broken line the compression end temperature should be at least 40‹C higher than the temperature in the first half of the compression range. In carrying out the invention air may be taken into a series of compressors, compressed and cooled between stages of compression. The cooling takes place only during the first part of compression the second part being uncooled. The air leaves the compressors substantially heated and is further heated by fuel combustion in a suitable heater. Thereafter the air is expanded in multstage turbine means being reheated by fuel combustion during expansion. The heating takes place only during the first part of the expansion, the second part being unheated. The series of turbines drive the series of compressors and excess power serves to drive an external load. Specification 410,544, [Group XXVI], is referred to. The Specification as open to inspection under Sect. 91 describes a gas turbine plant, Fig. 6 (Cancelled). Air taken in at 60 is compressed in a compressor 61. having coolers 62a-62d for the first part of the compression. The second half of compression is not cooled. At 62 the air passes to a regenerator 63 where it is heated and then to a combustion chamber 64. Expansion takes place in a turbine 65 with interstage combustion chambers 66a-c for reheating. The gases are finally expanded without reheating and discharged through the regenerator 63. This subject-matter does not appear in the Specification as accepted.